PSG vs Arsenal would surely be a tough one to predict. PSG barely won over Aston Villa and Arsenal surely is playing better than Aston Villa.
PSG eliminated Liverpool and it's quite hard to say Arsenal is playing better than Liverpool, especially the day one was crowned champions!
If you go by the direct match, Arsenal would be indeed the favorite but from the form, no PSG is still ahead of them at 3.2 compared to 3.5 to win the trophy.
The case for Arsenal at this time, besides benefiting from playing at home, they also greatly benefited from seeing PSG's current focus, especially in domestic competitions they are not in good condition so that indeed this could be a whip of more enthusiasm for Arsenal,
And Arsenal draws with Crystal Palace and Brentford are anything to brag about?
PSG has won the Ligue since April 5th, there is no point in them even playing with the first team in the remaining matches, it makes no sense to stretch your team over something you have no benefit from.